Even in the high-technology medical imaging arena, the decision of how to first image pediatric chest disease is quite simple: by plain chest radiograph, including frontal and lateral views. The diagnosis can often be made or suggested on the basis of these films or with other basic imaging procedures, such as fluoroscopy or esophagram. From this point onward the decision how to proceed with further imaging such as ultrasound, computed tomography, nuclear medicine imaging, or magnetic resonance imaging, will depend on the probability of gaining further helpful information. Beginning with a concise differential diagnosis allows one to proceed in a logical manner through the diagnostic work-up in a time-effective and cost-effective manner. One must keep in mind that in some cases the diagnosis cannot be made radiologically and must be left to the pathologist. In these cases the work-up should end when no further progress is possible toward making the diagnosis. In the pediatric age group, one should always strive to limit the amount of unnecessary radiation exposure.